This invention relates to a solar collector, and more particularly, to a flat plate energy absorber that uses thin films and is of simplified design.
There are a myriad of solar energy absorbers or collectors available. Generally, absorbers heretofore tend to be complicated and labor intensive. The simpliest of these systems employ involved plumbing schemes and absorber hardware that make even the "low cost" versions relatively expensive. Then, too, the overly complicated nature of prior apparatus comprises system reliability and detracts from system efficiency.
The present invention departs from standard practice and utilizes high performance, low cost thin films for the window of the collector and for the absorber. The thin films are bonded to the collector, or panel, in a stressed state and thus add to the overall strength of the panel. In general, the present invention comprises a rigid perimetric planar frame of light weight construction. A thin film, high strength plastic window or glazing is stretched across and bonded to one planar side of the frame. A thin film absorber, of laminate construction, defines a fluid-tight planar envelope through which a heat transfer fluid flows. The absorber is stretched across and bonded to the other planar side of the frame. The frame is thus stressed by the thin films on both planar sides yielding a panel of light weight monocoque construction that exhibits high strength. In the preferred structure, the absorber comprises two thin films that are perimetrically sealed. Means, in the form of a plurality of spot-welds or spot-bonds, are applied across the planar face of the absorber laminate for dimensional stability. By means of simplified input and output piping, the heat transfer fluid is admitted to and extracted from the absorber. In the preferred structure, the rigid members that comprise the frame are each, in transverse cross-section, defined by opposed, outwardly directed perimetric parallel flats. These flats provide a planar perimetric surface onto which the glazing and absorber bond. For added capacity, individual panels are readily joined in planar array by such means as contact bonding of adjacent planar perimetric flats. When the panels are so joined, the individual strength of a given panel enhances the overall strength of the array. The structural configuration of the frame readily accomodates the relative thermal expansion and contraction of adjacent panels thus minimizing structural fatigue.
It is, therefore, a object of the present invention to provide a low cost solar collector that is of simplified design.
It is another object of the present invention to provide a light weight, flat plate solar collector having a high degree of structural rigidity.
It is a further object of the present invention to provide a solar collector having a low cost, high strength absorber having good heat transfer to the fluid flowing through it.
It is still a further object of the present invention to provide a flat plate solar collector that is readily ganged in an ensemble or array of such collectors for added capacity, and wherein the strength of a given collector of the array adds to the strength of the other collectors of the array.
It is another object of the present invention to provide a low cost, light weight solar collector that eliminates the need for expensive fittings and other assembly hardware.
It is a still further object of the present invention to provide a solar collector of simplified design wherein the input and output piping forms a structure of integrated design with the collector.
It is one more object of the present invention to provide a low cost solar collector that can be installed on existing planar surfaces, such as roofs, with a minimum of labor, and that is capable of using such existing surfaces as backing insulation.
Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed for purposes of illustration only and not as a definition of the limits of the invention for which reference should be made to the appending claims.